Dampening system for an offset lithography machine



3,059,573 DAMPENING SYSTEM FOR AN OFFSET LITHOGRAPHY MACHINE Filed Aug. 26, 1960 Oct. 23, 1962 D. J. MARZULLO 2 Sheets-Sheet l DOM/N10 J. MARZULLO INVENTOR BY Ma 4% m ATTORNEY Oct. 23, 1962 D. J. MARZULLO DAMPENING SYSTEM FOR AN OFFSET LITHOGRAPHY MACHINE Filed Aug. 26, 1960 2 Sheets-Sheet 2 DOM/1W0 J. MARZULLO INVENTOR y 0 BY lt ATTORNEY Q. VI IWI IIA A w wu 8 SY wv w 6R United States Patent Ofifice 3,059,573 Patented Oct. 23, 1962 Dominic J. Marzullo, 6440 Gilmor Ave., Baltimore, Md. Filed Aug. 26, 1960, Ser. No. 52,098 2 Claims. (Cl. 101-148) This invention relates generally to printing apparatus, and more particularly it pertains to a system for dampening a plate cylinder in oflFset lithography machines.

Traditionally, rubber rollers have been used in offset presses both for linking and water etching the plate cylinder with its image plate. Except for special work, the practice has generally given way to the use of molleton covered water etching (dampening) rollers.

However, the presses still retain the complex arrangement necessary to uniformly distribute the etching water solution to either type dampening rollers, namely an intermediate vibrating metal roller, a ductor roller, and a fountain roller. The degree of dampening is controlled by oscillating and varying the length of time the ductor roller is in contact with the wet fountain roller which rotates within an open solution tray.

Among the shortcomings of the arrangement described above is the difficulty of maintaining the parallelism in the multiplicity of oscillating and vibrating rollers. As a consequence, incomplete dampening results in water bars on the printed matter. Other diificulties encountered are the contamination and the loss of etch water by unnecessary evaporation due to the large exposure area.

It is an object of the present invention to provide a simple, efiicient, pressure dampening system for offset printing presses which is readily controllable as to degree of dampening and which exposes a minimum of fluid to the atmosphere.

Another object of this invention is to provide a dampening roller having uniform wetting area and rapid response to moisture control.

Still another object of this invention is to provide an offset press having a minimum of mechanical parts to conceal the feed board and which is easy to maintain in adjustment and cleanliness.

And yet another object of this invention is to provide an etch Water system 'for offset presses which may be located remote from the press whereby the solution can he prepared, dispensed, maintained, and stored more efliciently than heretofore.

These and other objects and attendant advantages of this invention will become more readily apparent and understood from the accompanying specification and drawings in which:

FIG. 1 is a schematic drawing, partly in perspective, illustrating an oifset press pressure dampening system incorporating features of this invention;

FIG. 2 is a longitudinal section drawing of a slip coupling and a portion of a dampening roll; and

FIG. 3 is a cross section view taken along the line 3-3 of FIG. 2.

Referring now to the details of the drawings in FIG. 1 the pressure dampening system of this invention for use in oifset presses is designated generally by reference numeral 10. A plurality of parallel spaced ink transfer rollers 12 are shown in contact with a plate cylinder 14 around which an image plate (not shown) is wrapped.

A reservoir 16 is provided which is attached to a water supply line 18 through an intermediate control valve 20. The reservoir 16 is provided with a filler or access port 22 through which an etch chemical is introduced in the reservoir to make up the etch solution 26. A pump 24, communicating with the etch solution 26 is used to force it under pressure into a feed line 28 or optionally gravity feed of the etch solution may be used. 7

The feed line 28 is provided with a control valve 30, and, thence, it is attached to a length of flexible line 32. Another (feed line 34 at the farther end of this flexible line 32 is attached to a commercial rotary joint or slip coupling 36 which axially introduces the etch solution 26 into the interior of a pivoted dampening roller 42 and thence to its peripheral surface as will be related.

A pair of spaced rocker arms 38 and 40 are provided to support the slip coupling 36 and the dampening roller 42 and oscillate it against the plate cylinder 14 in synchronism with the operation of the press.

As shown best in FIG. 2, the slip'coupling 36 consists of a housing 44 which is secured to one rocker arm 38 by screws 46 and it is provided with a fluid tight intervening gasket 48. A conventional fitting 50 is used to attach the feed line 34 to the housing 44.

A compression coil spring 52 urges a co-axially apertured seal 54 against a shouldered tubular insert 58. The seal 54 is provided circumferentially with an O-ring 56 which is recessed in the housing 44. Insert 58 has an O-ring 60 similarly recessed within a bored out stub shaft 62 extending from the dampening roller 42.

This stub shaft 62 is machined from the body of the metal roller 64 of the dampening roller 42 and it provides for rotation thereof relative the upper end of rocker 38. A solid stub shaft (not shown) furnishes a pivot at the other end of the dampening roller 42 in conjunction with the rocker 40.

A plurality of radial passages 70 communciates at frequent intervals between a spiral groove 68 and a passage 66 on the outer surface and axial center, respectively, of the body of the metal roller 64 as shown in FIGS. 2 and 3. A liquid permeable sleeve 72 having a molleton textured surface is tightly and smoothly fitted over the body of the metal roller 64 and it becomes uniformly wetted with etch solution 26.

The simplicity of the novel pressure dampening system 10 is to be noted. When formerly two form dampening rollers, a vibration roller, a ductor roller, a fountain roller, and a liquid tray were used and all projected over the feedboard, only the one uniformly wet dispensing dampening roller 42 is now required in the operation field.

The liquid capacity of the various passages as related is low and they are quickly drained or filled. The response of the system 10 to valving consequently is rapid so that optimum water etch dispensing is easily maintained with the valve 30. Since liquid at only the active surface of the dampening roller 42 is exposed to the atmosphere, there is no chance for contamination or change in pH value thereof due to evaporation.

The etch solution 26 may be mixed directly in the reservoir 16 even while the press is in operation giving a decided advantage in'high production operation of the system 10. In addition, there is no danger of work spoilage from spilled etch solution 26 with a remotely located reservoir 16. .And finally, a superior work free of water bars results because there is but one roller 42 to maintain in parallelism with the plate cylinder 14.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination, an oflset lithography machine having a plate cylinder with an image plate positioned thereon, a plurality of parallel spaced ink transfer rollers in contact with said plate cylinder and arranged parallel thereto to transfer printing ink to said plate cylinder, means having a pivotally mounted dampening rol-ler positioned parallel to said plate cylinder and arranged to be moved for surface engagement with said plate cylinder as well as disengagement with said plate cylinder, said pivotally mounted dampening roller being formed of a metallic roller section having a cavity therein and a continuous spiralled groove of widely spread turns formed in its outer surface with radially formed passages connected between said cavity and spiralled groove, a liquid permeable sleeve having a molleton textured surrface tightly and smoothly fit-ted over said metallic roller section, a source of etch solution, and pressurizing means including a pump communicating with said source of etch solution and connected to said cavity for providing a uniform flow of said etch solution from said source of etch solution to said cavity and then to said radially formed passages and spiralled groove to said permeable sleeve having said molleton textured surface so that said sleeve surface becomes uniformly wetted with said etch solution.

2. In the combination as recited in claim 1, and additionally means having a slip coupling for said dampening roller to transfer said etch solution to said dampening roller.

References Cited in the file of this patent UNITED STATES PATENTS 1,173,523 Kuehn Feb. 29, 1916 1,643,488 Ehrlen et al Sept. 27, 1927 2,727,462 Alessi Dec. 20, 1955 2,777,744 Olden et a1. Jan. 15, 1957 2,913,980 Lindemann Nov. 24, 1959 FOREIGN PATENTS 813,599 Great Britain May 21, 1959 

